An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

A surrealist timepiece by the artist of melting clocks.

France's national museum of scientific and industrial instruments.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

A mechanized clock where a man fights off a dragon, crab, and rooster.

Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

A counter-culture bookstore like no other hides in plain sight in the streets of Paris.

A haunting collection of the vanished and disappearing natural world.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

Paris' linguistic guide to the international language of, yes, love.

A museum of carnival attractions where you are invited to ride the rides.

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

The oldest stone house in Paris was built by its most famous alchemist.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

France's most famous cemetery, with some of its most curious tombs.

This public library and its impressive collection of academic books have not changed since the 17th century.

The world's oldest Jewish library was founded by Sephardic Jews in 17th century Amsterdam.

This 8th-century Bavarian monastery is home to an exquisite Baroque-era library.

A grotto-like lodge decorated with gilded mosaics, rocks and a noisy waterfall was the setting for the most sumptuous pleasure house of 1900s Europe.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.